Batch Mode Biomethane Production from Anaerobic Digestion of Palm Oil Mill Effluent (POME) with Cassava Peels and Cabbage Waste

Abstract

This study aimed to investigate anaerobic co-digestion of palm oil mill effluent (POME) with cassava peels (CP) and cabbage waste (CW) for biomethane production. The anaerobic digestion (AD) in 10L capacity bioreactors loaded separately with three different ratios (3L/ 520g, 3L/ 600g and 3L/ 680g) of POME/CP, POME/CW and POME only (control) was operated under ambient temperature (25 - 36⁰C) and pH range of 6.5 - 8.5 for 45 days. Standard methods were adopted in the characterization of the bioreactor feeds and microbiological study. The biomethane content of the biogas was determined using Gas Chromatography (GC). The results showed the presence of Escherichia coli, Staphylococcus, Pseudomonas sp, Bacillus sp Salmonella sp among others. Fungal isolates identified include Saccharomyces, Aspergillus, Rhizopus, Penicillum, and Geotrichum species. The mean cumulative biogas yield recorded in bioreactors charged with POME/ CP 520g, POME/ CP 600g, POME/ CP 680g and POME/CW 520g, POME/CW 600g, POME/CW 680g were 7.08, 5.18, 9.06, 9.13, 9.28 and 8.33 dm3, respectively, whereas POME alone (control) was 4.64 dm3. The best performance in biogas yield was exhibited by POME/CW 600g (9.28dm3), and the highest percentage biomethane content (68.80%). Analysis of variance (ANOVA) revealed a significant difference (P ≤ 0.05) in biogas yield in all the treatments compared to control (POME alone) except in POME/CP 3L: 520g and POME/CP 3L: 600g. The results have shown that biogas production and biomethane content could be efficiently improved via co-digestion process, depending on the substrates used as feedstock.